GLOSSARY 559 



tween a scooter and a sweep. It is used to open a trench or 



furrow and is attached to the foot of a plow-stock. 

 Shredder. A machine for tearing into small pieces the coarse 



stems and other parts of corn stalks and other forms of 



coarse forage. See Fig. 98. 



Shucks. Corn shucks, the leaf -like parts inclosing the ear. 

 Sieve-tubes. Plant structures for the circulation of sap. 

 Silo. See p. 99. 

 Single-tree. The short wooden bar to which the traces of each 



horse or mule are hitched. 

 Slips. The slips of the sweet potato are also called "sets" and 



"draws." They consist of the young shoots growing out of 



the potato that is bedded. See Fig. 191. 

 Small grains. A term applied collectively to wheat, oats, rye, 



and barley in distinction from the larger grain, corn. 

 Smut. A disease of certain plants due to the growth of certain 



minute vegetable organisms. 

 Sorghum vulgare. The scientific name which is used by some 



authorities to include all the sorghums. 



Species. A group of plants having certain qualities in common. 

 Spelt. See p. 40. 

 Sphacelotheca sorghi. The scientific name of the fungus causing 



the kernel smut of the sorghums. See p. 233. 

 Sphceronema fimbriatum. The scientific name of the organism 



causing the black-rot of sweet potatoes ; until recently the 



first part of the name was usually written as Ceratocystis. 

 Spikelets. A small cluster of flowers or seeds. 

 Spores. Minute bodies which serve the purpose of seed for the 



fungi, that cause most plant diseases. 



Stamens. Anthers or pollen cases together with their supports. 

 Sterility. In plants, failure to produce a normal number of 



seed. 

 Stigma. The upper part of the pistil on which pollen must lodge 



and grow to effect fertilization of the flower. 

 Stomata. Minute openings in the outer layer of plant tissue, 



especially on the under sides of leaves, through which open- 

 ings the leaf gives off moisture and takes in carbon dioxide 



gas and oxygen. 



Strains. Subdivisions of a variety. 

 Subsoil plow. A plow for loosening without Inverting the soil. 



See Fig. 78. 



Subsoiling. See p. 163. 

 Subspecies. A division of a species. 

 Suckers. In the corn plant, stems springing from some of the 



lower nodes of the main stem. 

 Sucrose. Crystallizable sugar. 



